There was a king who had 600 servants. He had 100 for cooking, 100 for cleaning and building, 100 for farming, 100 for tending to the horses and trade caravans, 100 for delivering messages and items as well as attending to the needs of the nobles in his court, and 100 for guarding his estate. Every few days, he would have his magic mirror show him his servants one at a time as they worked so he could check on them and make sure that they weren't getting in trouble.
A rival king from far away declared war and laid siege to his home castle. The enemy forces managed to breach the gate and begin laying waste to the king's property and people. The guards eventually managed to drive them back, but only after some heavy losses.
The king had been informed that many of his servants had been killed or captured and taken to work for the rival king. To know just who was missing, he checked on each of them in his magic mirror. It showed him his distressed servants that lived and the corpses of those that were slain, but for some, the mirror could not show him and merely informed him that they were not found, which must have meant that they were captured and taken. The king became more and more crestfallen as he checked.
"39... this cook is alive but injured," he might have said.
"252: Farmer not found," the mirror might have said.
"380 dead... 381 dead... many now are alive... 402 lost an arm... 403 is weeping... Oh no! Please no!" the king cried.
"Damn! O Hell! He was my favorite! My most treasured! That rotten man!"
The king sobbed.
The mirror simply said, "404: Page not found"